With recent developments of the semiconductor industry, kinds and quantities of gases used therefor have been markedly increasing. Of these gases, gaseous hydrides are not only highly toxic but also flammable and, therefore, should be handled with sufficient care.
Therefore, on handling these gases, detection in a working atmosphere should constantly be carried out. In cases where these gases leak out by any possiblity, a proper and well-timed measure should be taken to notify the workers of the leakage.
On the other hand, since exhausted gases discharged from the production step of semiconductors contain these gaseous hydrides, it is cleaned by means of a waste gas purifying device, etc., before discharge to an open atmosphere. In this case, also, it is necessary to confirm removal of these gaseous hydrides before the waste gas is discharged.
Known methods of detecting the aforesaid gaseous hydrides utilize color change of a detecting reagent packed in a glass tube which is caused by reaction between the detecting reagent and a gas to be detected. Conventionally known detecting reagents include, for example, mercury (II) or a complex salt thereof or a mixture thereof with a ferric salt or a cupric salt adsorbed on silica gel particles for detecting phosphine; and chemicals consisting of gold adsorbed on silica gel particles for detecting phosphine, arsine or diborane.
However, each of these known detecting reagents is capable of detecting only limited kinds of gases so that gases detectable by one kind of a detector tube are so limited. Moreover, after these detecting reagents once undergo color change, they return to their original color with the passage of time. This incurs the possibility of passing over the color change in cases when gaseous hydrides exist only temporarily. Further, detecting reagents that are of practical utility in detection of monosilane and disilane have not yet been developed. Under these circumstances, there is no means for detection this is commonly applicable to all of the gaseous hydrides used in the production of semiconductors, etc., with high sensitivity.
In addition to the above-described detector tubes, a detecting method for gaseous hydrides by means of a detecting alarm based on several ideas is also known. However, such an alarm is also limited in kind of gases to be detected and, in addition, is complicated in measurement principle and structure.
Accordingly, it has been highly desirable to develop a detecting reagent which can be applied to various kinds of gaseous hydrides and suffers less color disappearance after color change.